To date few detailed chemical studies have been carried out on mammalian messenger RNAs (mRNAs). The overall aim of our project is to characterize the mRNA in mouse myeloma cells, emphasizing in particular the specific messengers for immunoglobulins. Mouse myeloma cells have been selected for this study because they are monoclonal cells which grow rapidly in culture (essential for effective radioactive labelling of RNA) and synthesize significant amounts of a single species of immunoglobulin. They thus constitute an excellent system for the combined study of total mRNA and the specific immunoglobulin messengers. We plan to apply nucleotide sequencing techniques to investigate certain general features of the total myeloma mRNAs, in particular the newly discovered highly unusual 5'-terminal sequences and the modified nucleotides in the RNA. Heterogenous nuclear RNA classes will also be analysed in order to define better their relationship to cytoplasmic mRNA. We also plan to carry out very detailed studies on immunoglobulin light chain mRNA to (a) identify the 5'-terminal sequence and any modified nucleotides in the RNA and (b) to determine extensive nucleotide sequences in all parts of the molecule, including both coding and non-coding regions. It is hoped that this work will contribute to the understanding of immunoglobulin biosynthesis and of the general structure of eucaryotic mRNA. BIBLIOGRAPHIC REFERENCES: Nucleotide sequence in the 3'-terminal non-coding sequence of an immunoglobulin kappa chain mRNA determined by analysis of complementary DNA. Bernard, O., Jackson, J., Cory, S. and Adams J. Biochemistry, in press (1977). Synthesis of RNA on RNA templates using the DNA-dependent RNA polymerase of Escherichia coli. Bernard, O., Cory, S. and Adams, J. Biochim. Biophys. Acta., in press (1977).